Beyond Mean Climate: Quantifying Climate Variability and Extremes under Varying Boundary Conditions

超越平均气候：量化不同边界条件下的气候变化和极端情况

• 批准号: 2303149
• 负责人: Tyler Jones
• 金额: $ 123.78万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-01 至 2026-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2303149&HistoricalAwards=false
• 关键词: Beyond; Mean; Climate; Quantifying; Variability

The Earth’s climate can be defined broadly by two concepts, average values and variability around those averages; for example the average temperature of a location over some interval and how much the temperature varies from that average on any given day, or month, or year, or decade. This variability is important to human societies, driving things like extreme heat waves or droughts. Over Earth’s long history, the average climate has changed in profound ways. For example, 20,000 years ago, the Earth on average was about 5 degrees Celsius colder, and large glaciers covered parts of continents that are ice free today. We know that the average climate has changed because we have evidence from natural archives, such as that found in the chemistry of ice that remains frozen at the poles. But how has the variability changed? Does the variability change with the same pattern as the average? How often do extreme events - such as extremely hot or cold temperatures - occur at different times in the past? Records of the year–to-year or decade-to-decade variability, say from 20,000 years ago, are exceptionally rare. We will use climate records from very high-resolution measurements of ancient polar ice in Greenland and Antarctica, obtained through a process known as ‘ice coring’, to study the inherent variability in Earth’s climate and how it changes over long periods of time, extending backwards in time up to 100,000 years before present. These aspects of climate, the variability and extremes, in addition to the average climate, can provide new contexts that help us better understand our changing planet.The relationship between the mean climate and its internal variability is a fundamental aspect of climate dynamics. Understanding the dependence of internal variability on the mean state is key to understanding the detectability of forced changes in climate and, critically, the change in likelihood of extreme events. Information about internal climate variability throughout Earth’s history, as the mean climate has undergone large changes, such as during the Last Glacial Maximum about 20,000 years ago, is exceedingly rare. Most paleoclimate archives lack the detail or continuity to reliably resolve annual, interannual, and decadal timescales for tens of thousands of years. We will use a suite of five extremely high-resolution ice core records of water isotopes, as well as impurities like dust, to statistically catalog variability and extremes in polar climate and its relationship to the background mean state. We will examine these relationships over periods of stable mean climate, long term changes in global mean climate, as well as abrupt climate change, and provide an unprecedented analysis of high-frequency, high-latitude climate variability. The analysis will span the last glacial-interglacial cycle, extending backwards in time up to a 100,000 years into the past. High-frequency climate variability has been impactful to humans and societies throughout history. Annual, interannual, decadal, and centennial scale variability has driven changes in habitability leading to the blossoming and collapse of past civilizations. Extreme climate events in particular affect modern quality of life, national security, food and water availability, and ecosystem services (among other concerns). The proposed research on climate variability and extremes of the past, and the relationship to average climate, can provide new contexts that help us better understand our changing planet.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

地球的气候可以通过两个概念来定义，平均值和平均值周围的变化;例如，一个位置在某个时间段内的平均温度以及在任何给定的一天，一个月，一年或十年内温度与平均值的变化。这种可变性对人类社会很重要，导致极端热浪或干旱等事件。在地球漫长的历史中，平均气候发生了深刻的变化。例如，20，000年前，地球平均温度下降约5摄氏度，大型冰川覆盖了今天无冰的部分大陆。我们知道平均气候已经发生了变化，因为我们有来自自然档案的证据，例如在两极仍然冻结的冰的化学中发现的证据。但变异性是如何变化的呢？变异性是否以与平均值相同的模式变化？在过去的不同时间，极端事件（如极热或极冷的温度）发生的频率如何？ 年与年或十年与十年的变化记录，比如从20,000年前开始，是非常罕见的。我们将使用格陵兰岛和南极洲古代极地冰的高分辨率测量的气候记录，通过一个被称为“冰取芯”的过程获得，以研究地球气候的固有变化以及它在很长一段时间内如何变化，在时间上向后延伸到现在之前的10万年。气候的这些方面，变异性和极端，除了平均气候，可以提供新的背景，帮助我们更好地了解我们不断变化的地球。平均气候和其内部变异性之间的关系是气候动力学的一个基本方面。了解内部变率对平均状态的依赖性是了解气候强迫变化的可探测性的关键，关键是了解极端事件可能性的变化。关于地球历史上内部气候变化的信息，因为平均气候经历了巨大的变化，例如在大约20，000年前的末次冰期最大期，是非常罕见的。大多数古气候档案缺乏细节或连续性，无法可靠地解决数万年的年度，年际和十年的时间尺度。我们将使用一套五个极高分辨率的水同位素冰芯记录，以及灰尘等杂质，对极地气候的变化和极端情况及其与背景平均状态的关系进行统计编目。我们将在稳定的平均气候、全球平均气候的长期变化以及气候突变的时期内研究这些关系，并对高频率、高纬度的气候变率进行前所未有的分析。分析将跨越最后一次冰期-间冰期循环，时间上向后延伸到过去的10万年。在整个历史上，高频率的气候变率一直对人类和社会产生影响。年度、年际、十年和百年尺度的变化推动了可居住性的变化，导致了过去文明的繁荣和崩溃。极端气候事件尤其影响到现代生活质量、国家安全、粮食和水的供应以及生态系统服务（以及其他关切）。该奖项旨在研究过去的气候变化和极端事件，以及与平均气候的关系，可以提供新的背景，帮助我们更好地了解我们不断变化的地球。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。